Currently the transfer of loaded containers between land and ships involves the use of a relatively large marine terminal crane having a single rail for guided travel of a trolley along the length of a boom. A spreader bar is suspended from the trolley through which the containers are raised and lowered by the crane during performance of a time-consuming load transfer process. For small scale ports with low demands, a highly efficient load transfer performance may not be required. However, at larger ports the crane has been a main bottleneck in disrupting and rendering inefficient marine terminal activities related to loading and unloading of shipping vessels. Such activities involve the crane operator simply lowering the crane spreader bar so as to lock onto a container anywhere below the crane. Often a time consuming process is involved because multiple attempts are required before successful landing of the spreader bar on the container and lock on is achieved leading to a line-up of many trucks awaiting pick up of containers from the crane to thereby delay use of such trucks in acquiring another container.
It is therefore an important object of the present invention to provide for more efficient and less time consuming transfer of the containers and more productive use of the crane and the trucks, while using currently designed marine terminal cranes.